The present invention relates to a method for cleaning dialysate pipes in a hemodialysis system after completion of dialysis, and more particularly to a method for cleaning a hemodialysis system that is effective for preventing carbonates, proteins, bio-films and the like from adhering and is excellent in sterilizing property.
xe2x80x9cDialysisxe2x80x9d is a therapeutic method in which, by combining the principles of diffusion and osmosis or filtration, aetiologic substances existing in a body fluid are brought into contact with a dialysate and removed, thereby maintaining the homeostasis of the body fluid. This therapeutic method comprises: guiding the blood of a patient to the outside of the body; causing the blood to pass through an artificial kidney (dialyzer) which carries out dialysis; bringing the blood and a dialysate into contact with each other via a semi-permeable membrane in the artificial kidney; causing aetiologic substances contained in the blood to move into the dialysate; and returning the blood thus cleaned into the body of the patient.
xe2x80x9cHemodialysis systemxe2x80x9d generally comprises: a pipe for guiding dialyzing water, which is connected with an artificial kidney for carrying out blood dialysis, blood filtration, blood filtration dialysis or the like; a pipe for guiding a dialysate in which a chemical for dialysis is dissolved into the dialyzing water; a pipe for draining the dialysate; flow rate controlling pumps interposed therebetween and the like. The pipes for guiding dialysate mainly include: a pipe for supplying dialyzing water; a water supply tube for supplying the artificial kidney with the dialysate in which a chemical for dialysis is dissolved in the dialyzing water; and a water drainage tube for draining the dialysate from the artificial kidney. After connecting (1) a line for guiding blood of a patient to the artificial kidney, (2) the artificial kidney and (3) a line for returning the blood having been dialyzed through the artificial kidney to the patient, dialysis is carried out. After completion of dialysis, the artificial kidney and the lines for blood that are connected to the artificial kidney in Japan are disposed of. Meanwhile, the pipes for the dialyzing water and the dialysate are cleaned and recycled. Cleaning of these pipes is generally accomplished by connecting the pipes removed from the artificial kidney with a coupler connector and causing a cleaning solution to flow therethrough.
Heretofore, for the purpose of cleaning dialysate pipes in a hemodialysis system, reagents such as sodium hypochlorite, acetic acid, and peracetic acid have been used. Although cleaning by the use of such reagents can sterilize microorganisms, there is a case that calcium carbonate and proteins are adhered to the pipe portions of the hemodialysis system, and moreover there is a case that bio-films (mixed layers composed of dead bacteria, calcium carbonate and the like) are gradually accumulated. Such bio-films are very difficult to be removed once having adhered to the pipes. In order to prevent these carbonates, proteins and bio-films from adhering, cleaning is carried out by alternately using plural reagents having different characteristics.
Meanwhile, in Japanese Unexamined Patent Publication JP-A 7-171212 (HEI-7, 1995) which discloses simplifying a dialysis drainage operation, a method for cleaning an artificial hemodialysis therapeutic system which utilizes ozone water and an apparatus for implementing the method are disclosed. In this method, ozone is generated from RO water by an apparatus for producing ozone which generates ozone in response to the RO water, then the RO water and the ozone are mixed again to form ozone water, and thereafter a cleaning operation of the dialysate pipes in the artificial hemodialysis therapeutic system is carried out. In the above method, the RO water is purified from raw water at an apparatus for producing pure water 1. The ozone is generated in an electrobath 10 of an apparatus for producing ozone 2, and outputted while being separated from the RO water in a gas/liquid separating tank 11. In the case of a cleaning operation, the RO water from the apparatus for producing pure water 1 and the ozone from the apparatus for producing ozone 2 are mixed and outputted as ozone water. On the other hand, in the case of dialysis therapy, the RO water from the apparatus for producing pure water 1 is outputted as it is. However, in this cleaning method, it is considered that in the course of mixing the generated ozone with the RO water, the ozone itself is extinguished so that the concentration of the ozone water reaching the hemodialysis therapeutic system is necessarily relatively lower compared to that at the time of generation. Therefore, it is considered that the cleaning efficiency thereof is lower than desired.
Moreover, in the above patent publication, there is no clear description about the efficiency of preventing adhesion of carbonates, proteins, bio-films and the like, and about the optimum ozone concentration of the ozone water.
The present invention has been made in consideration of the above problems, and it is an object of the present invention to provide a method for cleaning dialysate pipes of a hemodialysis system using high concentration ozone water, which is effective for preventing adhesion of carbonates, proteins, bio-films and the like and excellent in sterilizing property.
As a result of due consideration for achieving the above-mentioned object, the inventors of the present invention have found that adhesion of calcium carbonate, proteins, bio-films and the like to the dialysate pipes of the hemodialysis system can be prevented, while realizing cleaning with an excellent sterilizing property, when an apparatus for producing high concentration ozone water is used as the apparatus for producing ozone, and a setting is made to achieve an average ozone concentration at the time of draining ozone water of less than 2 ppm. These findings led to the present invention.
More specifically, the present invention is a method for cleaning a hemodialysis system after completion of dialysis, characterized in that ozone water generated by an apparatus for producing high concentration ozone water is sequentially introduced after completion of dialysis to dialysate pipes of the hemodialysis system including a water supply tube for supplying dialyzing water, a water supply tube and a water drainage tube for dialysate, and then the ozone water is drained from the water drainage tube.
Also, the present invention is a method for cleaning a hemodialysis system in which cleaning is carried out by using high concentration ozone water generated by the water electrolytic process, characterized in that an average ozone concentration at the time of draining the ozone water is not less than 2 ppm.